Aluminum alloy composition for die casting

ABSTRACT

Disclosed is an aluminum alloy composition for die casting, including 0.85 to 1.2 wt % of copper, 0.15 to 0.2 wt % of silicon, 0.08 to 0.1 wt % of magnesium, 0.08 to 0.12 wt % of zinc, 1.5 to 2.5 wt % of iron, and inevitable impurities, with the remainder of aluminum. This aluminum alloy composition for die casting can exhibit superior mechanical properties and thermal conductivity, and can be prevented from sticking to a mold, thereby increasing die-casting efficiency.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of Korean Application No. 10-2017-0098100 filed on Aug. 2, 2017 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION Technical Field

The present invention relates to an aluminum alloy composition for die casting, and more particularly to an aluminum alloy composition for die casting, which exhibits superior mechanical properties and thermal conductivity and is prevented from sticking to a mold, thus increasing die-casting efficiency.

Description of the Related Art

An aluminum alloy is lightweight and strong and is thus widely used as a durable material. Particularly, in recent years, it is mainly utilized for cases for electronic products, such as mobile phones, or for automobile parts. Typically, two processes are mainly applied in order to manufacture a product using aluminum.

First, a pressing process is performed in a manner in which an aluminum plate is pressed to thus form a case, the surface of which is then formed with an anodized film, thereby obtaining a case having a surface having a beautiful color without damaging the surface portion, even upon long-term usage. However, when the case is manufactured by pressing the aluminum plate, it is difficult to ensure space to mount parts inside the case and to form a rib for reinforcement and a boss for screw connection. Furthermore, the design of the case is limited because there is a shape that cannot be formed by the pressing process.

Second, a die-casting process is applied. When a case is manufactured by the die-casting process, it is easy to form a space for seating parts to be mounted inside the case, a boss for screw connection, and a rib for strength reinforcement, thus enabling design of the case as desired. However, the conventional aluminum alloy for die casting has relatively low mechanical strength and thermal conductivity, and the composition for aluminum alloy sticks to the mold during the die-casting process, undesirably lowering die-casting efficiency.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the problems encountered in the related art, and the present invention is intended to provide an aluminum alloy composition for die casting, which may exhibit superior mechanical properties and thermal conductivity and may be prevented from sticking to a mold, thus increasing die-casting efficiency.

An embodiment of the present invention provides an aluminum alloy composition for die casting, comprising 0.85 to 1.2 wt % of copper, 0.15 to 0.2 wt % of silicon, 0.08 to 0.1 wt % of magnesium, 0.08 to 0.12 wt % of zinc, 1.5 to 2.5 wt % of iron, and inevitable impurities, with the remainder of aluminum.

Preferably, copper is contained in an amount of 0.9 to 1.0 wt %.

More preferably, iron is contained in an amount of 1.7 to 2.2 wt %.

According to the present invention, an aluminum alloy composition for die casting can exhibit superior mechanical properties and thermal conductivity and can be prevented from sticking to a mold, thus increasing die-casting efficiency.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a detailed description will be given of preferred embodiments of the present invention and properties of individual components, which is merely set forth such that the present invention may be easily performed by those of ordinary skill in the art to which the present invention belongs, but is not to be construed as limiting the spirit and scope of the present invention.

The present invention addresses an aluminum alloy composition for die casting, comprising 0.85 to 1.2 wt % of copper, 0.15 to 0.2 wt % of silicon, 0.08 to 0.1 wt % of magnesium, 0.08 to 0.12 wt % of zinc, 1.5 to 2.7 wt % of iron, and inevitable impurities, with the remainder of aluminum.

Specifically, copper is contained in an amount of 0.85 to 1.2 wt %, and functions to increase thermal conductivity as well as the strength and hardness of the disclosed aluminum alloy composition for die casting, thereby increasing die-casting efficiency.

If the amount of copper is less than 0.85 wt %, the above effects become insignificant. On the other hand, if the amount of copper exceeds 1.2 wt %, the corrosion resistance of the aluminum alloy composition for die casting is remarkably decreased.

Taking into consideration the improvement in thermal conductivity and corrosion resistance, the amount of copper is preferably set to the range of 0.9 to 1.0 wt %.

Silicon is contained in an amount of 0.15 to 0.2 wt %, and functions to improve casting performance during the die-casting process because it increases the fluidity and strength of the disclosed aluminum alloy composition for die casting. More specifically, silicon is subjected to bonding with magnesium and then aging and is thus precipitated into Mg₂Si, thereby exhibiting mechanical properties. Furthermore, silicon remaining after bonding with magnesium (Mg) may be precipitated alone to thus improve the mechanical properties and the fluidity of a melt.

Silicon is an element that improves the fluidity of an aluminum alloy and the strength thereof. When silicon is contained in a large amount, castability becomes good but brittleness becomes high due to the formation of a magnesium silicide (Mg₂Si) phase and an acicular silicon phase. Hence, the amount of silicon is preferably set to the range of 0.15 to 0.2 wt %. If the amount of silicon is less than 0.15 wt %, the enhancement in the strength of the aluminum alloy composition for die casting becomes insignificant. On the other hand, if the amount of silicon exceeds 0.2 wt %, the brittleness of the aluminum alloy composition for die casting is excessively increased, thus deteriorating mechanical properties.

Magnesium is contained in an amount of 0.08 to 0.1 wt %, and functions to form a precipitate phase of the aluminum alloy composition for die casting and to improve the tensile strength and mechanical properties thereof.

If the amount of magnesium is less than 0.08 wt %, the above effects become insignificant. On the other hand, if the amount of magnesium exceeds 0.1 wt %, inclusions may be generated due to oxidation and properties and castability may decrease, and furthermore, elongation of the aluminum alloy composition for die casting may decrease.

Zinc is contained in an amount of 0.08 to 0.12 wt %, and precipitates a zinc-magnesium-based reinforced phase through reaction with magnesium. Although zinc is ductile at room temperature, when the temperature rises, ductility increases and an aggregated texture is formed in the material that has been subjected to predetermined processing, so that anisotropy appears in the mechanical properties and corrosion of the product is prevented.

If the amount of zinc is less than 0.08 wt %, the above effects become insignificant. On the other hand, if the amount of zinc exceeds 0.12 wt %, the strength of the aluminum alloy composition for die casting is excessively increased, thus deteriorating die-casting efficiency.

Iron is contained in an amount of 1.5 to 2.5 wt %, and functions to enhance the bonding strength of aluminum and components such as copper, silicon, magnesium and zinc during the die-casting process, thereby preventing subdivision.

If the amount of iron is less than 1.5 wt %, the prevention of subdivision is insignificant. On the other hand, if the amount of iron exceeds 2.5 wt %, the effect of preventing subdivision is not greatly improved, and the toughness of the aluminum alloy composition for die casting is lowered, and moreover, the dissolution temperature may rise, thus deteriorating castability.

Moreover, iron may contribute to an increase in the density of an alloy to thus enhance strength, and in addition, demolding performance may be improved through a reduction in stickiness, coarsening of recrystallized grains is suppressed, and an effect of fining the grain size during casting is exhibited. If the amount of iron exceeds 2.5 wt %, ductility may be decreased and extrudability and productivity may be lowered.

Taking into consideration the dissolution temperature as well as preventing subdivision and decreased toughness, the amount of iron is preferably set to the range of 1.7 to 2.2 wt %.

Below is a description of a method of preparing an aluminum alloy composition for die casting and the properties of an aluminum alloy composition for die casting prepared thereby, made with reference to the following example.

Example 1

96.64% of aluminum was heated to 950° C., after which 1.0 wt % of copper and 0.17 wt % of silicon were added thereto, and the mixture added with silicon was heated to 1200° C., after which 0.09 wt % of magnesium and 0.1 wt % of zinc were added thereto, and the mixture added with magnesium and zinc was heated to 1550° C., after which 2.0 wt % of iron was added thereto and the mixing process was performed. The resulting mixture was cooled to room temperature, thereby preparing an aluminum alloy composition for die casting.

The hardness of the aluminum alloy composition for die casting of Example 1 was measured. The results are shown in Table 1 below. (The hardness of the aluminum alloy composition for die casting was determined in a manner in which the aluminum alloy composition for die casting of Example 1 was formed to a thickness of 4.05 mm and then tested using a Brinell hardness tester.)

TABLE 1 No. Hardness Remark Example 1 37.1 HBW (10 mm/500 kgf)

As is apparent from Table 1, the aluminum alloy composition for die casting of Example 1 exhibited superior mechanical properties.

Therefore, the disclosed aluminum alloy composition for die casting exhibits superior mechanical properties and thermal conductivity and is prevented from sticking to a mold, thus increasing die-casting efficiency.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 

What is claimed is:
 1. An aluminum alloy composition for die casting, comprising 0.85 to 1.2 wt % of copper, 0.15 to 0.2 wt % of silicon, 0.08 to 0.1 wt % of magnesium, 0.08 to 0.12 wt % of zinc, 1.5 to 2.5 wt % of iron, and inevitable impurities, with a remainder of aluminum.
 2. The aluminum alloy composition of claim 1, wherein the copper is contained in an amount of 0.9 to 1.0 wt %.
 3. The aluminum alloy composition of claim 1, wherein the iron is contained in an amount of 1.7 to 2.2 wt %. 